Ok I myself came up with a solution. This is not a complete animation, but it works for me.
Basically what I do, I load the wfs layer on my map. Now here's the trick: When I do this, I just sort the time values of the functions one by one and add each function with a time value from 1 to one level, and each function has a time value from 2 to another and so on. This basically does the trick. The rest is simple.
The next step is that I implement a slider that ranges from 1 (the lowest time value) to any highest time value. Each time the engine moves, it fires an event that determines what time value the slider is set to, and then adds / removes the corresponding layers.
So, if the slider is set to 5. It will add each layer from 1 to 5 to the map and delete all other layers. Again, this is not an animation, but it works in my case.
If someone comes up with another possible solution, post it here. I would appreciate.
(Btw, this is what my solution looks like in action :)

EDIT: Now I can also confirm that with this approach you can create the “right” animations. I just built a js function that includes a few "setTimeout" until the time the layer is added, and a play button is added that launches this function. This means an animation that visualizes growth from t = 1 to tmax.
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